The might be talking about peak wattage. Antec uses the rated wattage, they call it "true wattage". A rated 350 watt power supply is all you need for a 6800 gt, and that Antec is a rated 480 watt. Don't worry about it, you have plenty of power.
And I have that same power supply except not the blue one and it powers all the crap in my sig easily along with some case fans and cd burners and stuff.